Digital video encoding algorithms, for example MPEG-X series, utilize a process for digital quantization of video information. The quantization process involves approximation of analog video information, for example an analog picture image, by a frame consisting of numerous pixels having the brightness and color attributes. Further MPEG-X series algorithms use such a compression technique that assumes a certain loss of video information. This means that after encoding-decoding procedure the pixels of the digitized video information differ from the original corresponding pixels with color and brightness. On the one hand, such a technique allows a substantial compression of the video information, and the quality of the image may be perceived to be more brimful than real, but on the other hand, several sequential repeats of the encoding-decoding procedure cause a substantial degradation of the video information. The MPEG-X series algorithm technique is based on the grouping of the pixels into “quantization blocks”, such that all the pixels belonging to a particular block are coded separately, i.e. have the same brightness and color quantization rule leading to a certain degradation of video information. Usually the quantization rule is defined by quantization step chosen for each quantization block separately. Such an approximation of the video information allows reducing a bit stream of information by decreasing the video information resolution. These blocks may be grouped into macro-blocks to use a transferring vector for the approximation of the video information of the next frame, thereby further reducing the required bandwidth of the bit stream of information. In the case of movies, a tolerance of video information loss related to pixels aggregated into blocks may differ from one block to another and from a frame to the next one. This degree of freedom permits tracking of the picture elements from one frame to the next thereby further reducing the required bandwidth for the stream of bit information, in principal.
Thus known video compression procedures attempt to achieve increased resolution and decreased bandwidth requirements for transmitting video information by using different kinds of quantization rule for each block. Prior art blocks, which are used in MPEG-X algorithms, have form of rectangles arranged as it is shown in FIG. 1. In this case each rectangular block has eight neighbors: North, North-West, West, South-West, South, South-East, East and North-East. A degradation of the video information within each block is controlled by the quantization rule, however the degradation of video information on boundaries of the considered block with neighbor blocks is unpredictable in a certain meaning. If blocks and macro-blocks, defined for a frame, are transferred by a transferring vector in order to approximate the video information of the next frame, a statistical error in the imagination of the next frame is defined by the block neighbors, having independent attributes of color and brightness quantization rule, wherein, as it is described, for example, by Torsten Seemann and Peter Tischer and Tetra Lindarto in the paper titled “Generalised Locally Adaptive DPCM”—Proc. of IEEE Data Compression Conf., pp473, 1997, the error arises on the block boundaries.
U.S. Pat. No. 5,764,805 to Martucci, et al. discloses the use of overlapping polygonal shaped blocks for reducing statistical errors appearing at the quantization block boundaries.